Method for calculating a linearization curve for determining the fill level in a container the use of a mobile end device for said method

ABSTRACT

Method for calculating a linearization curve for determining the fill level in a container from a filling height, said method comprising the following steps: acquiring three-dimensional data of the container with a mobile end device, having at least one optical camera, a depth sensor and a motion detector, establishing a three-dimensional model of the container, and calculating the linearization curve from the three-dimensional model for determining a fill level from a measured filling height.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application claims priority to German Patent Application 102016 111 570.3, filed on Jun. 23, 2016.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

No federal government funds were used in researching or developing thisinvention.

NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT

Not applicable.

SEQUENCE LISTING INCLUDED AND INCORPORATED BY REFERENCE HEREIN

Not applicable.

BACKGROUND Field of the Invention

The invention relates to a method for calculating a linearization curvefor determining the fill level in a container the use of a mobile enddevice for said method.

Background of the Invention

The present invention relates to a method for calculating alinearization curve for determining the fill level in a container from afilling height in accordance with the preamble of patent claim 1 and tothe use of a mobile end device for this method in accordance with patentclaim 8.

The present invention relates to the field of process measuringtechnology and in this case, particularly to the technology of measuringthe fill level. To determine the fill level in a container, the standardprocedure in level measuring technology is to calculate the fill level,based on a filling height. In this case, the filling height can bedetermined in a number of ways. Known methods for determining thefilling height in a container are, on the one hand, starting from thebottom of the container, the hydrostatic determination of a fillmedium-induced pressure level, and, on the other hand, starting from thecover lid of the container, the determination of the distance between asensor position and a surface of the filling material by means of radar,guided radar, ultrasound, in a capacitive manner or by means of othersuitable methods; or the determination of discrete limit levels insidethe container, starting from, for example, a side wall of the container.

All of the aforementioned methods have in common that the citedmeasurement methods do not determine the fill level of the container,but rather determine only a filling height inside the container. Thecorrelation between a filling height and the fill level is described bya so-called linearization curve that describes, as a function of acontainer geometry and any built-in components in the container, afunction for converting the filling height into the fill level.Commensurate linearization curves can be calculated in the period onlyextremely inaccurately by means of manual measurements and with the aidof linearization tables. In the case of the methods known from the priorart for this purpose, it is not possible to consider or it is possibleonly to a limited extent to consider, for example, irregularities insidethe container and/or the effects of built-in components in containerswhen determining the fill level.

This is where the present invention come in.

The object of the present invention is to provide a method forcalculating a linearization curve for determining the fill level in acontainer from a filling height, by means of which a higher degree ofmeasuring accuracy can be achieved.

This object is achieved by means of a method exhibiting the featuresdisclosed herein and by means of the use of a mobile end device that isintended for this method and that exhibits the features also disclosedherein.

BRIEF SUMMARY OF THE INVENTION

In a preferred embodiment, a method for calculating a linearizationcurve (L) for determining the fill level (F) in a container (10) from afilling height (h), characterized by the following steps:

-   -   acquiring two dimensional data and a reference value of a        container (10) having a symmetry with a mobile end device,        having at least one optical camera (14)    -   entering the type of symmetry    -   establishing a three dimensional model (8) of the container        (10),    -   calculating the linearization curve (L) from the three        dimensional model (8) for determining a fill level (F) from a        measured filling height.

In another preferred embodiment, a method for calculating alinearization curve (L) for determining the fill level (F) in acontainer (10) from a filling height (h), characterized by the followingsteps:

-   -   acquiring three dimensional data of the container (10) with a        mobile end device (12), having at least one optical camera (14),        a depth sensor (16) and a motion detector (18),    -   establishing a three dimensional model (8) of the container        (10),    -   calculating the linearization curve (L) from the three        dimensional model (8) for determining a fill level (F) from a        measured filling height.

In another preferred embodiment, the method as described herein,characterized in that the three dimensional data of at least one outershell (101) of the container (10) are acquired.

In another preferred embodiment, the method as described herein,characterized in that, in addition, a material thickness (d) of thecontainer is entered.

In another preferred embodiment, the method as described herein,characterized in that the three dimensional data of an inner shell (102)of the container (10) are acquired.

In another preferred embodiment, the method as described herein,characterized in that the acquisition of the three dimensional data ofthe container (10) occurs in accordance with one or a combination of themethods: time of flight, structured light or stereoscopy.

In another preferred embodiment, the method as described herein,characterized in that the three dimensional acquisition of the container(10) is supported by means of a database with three dimensional data ofpossible built-in components.

In another preferred embodiment, the method as described herein,characterized in that, in addition to the linearization curve (L), asuitable fill level measuring method and/or an optimized position for afill level sensor is/are determined and outputted.

In another preferred embodiment, the use of a mobile end device (12)having at least one optical camera (14), for acquiring preferably threedimensional data of a container (10), for establishing a threedimensional model (8) of the container (10) as well as for calculating alinearization curve (L) for determining a fill level (F) from a fillingheight.

In another preferred embodiment, the use of a mobile end device (12)having at least one optical camera (14), a depth sensor (16) and amotion detector (18) for acquiring three dimensional data of a container(10), for establishing a three dimensional model (8) of the container(10) as well as for calculating a linearization curve (L) fordetermining a fill level (F) from a filling height.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a line drawing evidencing an exemplary container and a mobileend device.

FIG. 2 is a line drawing evidencing the mobile end device from FIG. 1.

FIG. 3A) is a line drawing evidencing a three-dimensional model of thecontainer from FIG. 1.

FIG. 3B) is a line drawing evidencing a linearization curve calculatedfrom this three-dimensional model.

DETAILED DESCRIPTION OF THE INVENTION

The invention comprises an inventive method for calculating alinearization curve for determining the fill level in a container from afilling height is characterized by the following steps:

-   -   acquiring two-dimensional data and a reference value of a        container (10) having a symmetry with a mobile end device,        having at least one optical camera (14)    -   entering the type of symmetry    -   establishing a three-dimensional model (8) of the container        (10),    -   calculating the linearization curve (L) from the        three-dimensional model (8) for determining a fill level (F)        from a measured filling height.

According to the present invention, two-dimensional data of thecontainer and a reference value are acquired with the aid of a mobileend device, for example, a tablet computer, a mobile telephone or anyother suitable mobile end device, which has at least one optical camerafor capturing and visualizing an image of the container. Thetwo-dimensional data of the container, the reference value andinformation about the symmetry of the container can be used to create,preferably with the mobile end device, a two-dimensional model of thecontainer with a high degree of accuracy. Preferably thethree-dimensional model of the container is vector-based.

As soon as the three-dimensional model of the container is completelyfinished and available for the relevant parts of the container, saidthree-dimensional model of the container can be used to calculate,preferably with the mobile end device, the linearization curve fordetermining the fill level in the container, based on a measured fillingheight. Since the three-dimensional model of the container that isestablished in this way and the linearization curve that is calculatedfrom said three-dimensional model take into account the actual localconditions, it is possible to consider, in particular, theirregularities of the container, the built-in components and/or otherspecial features when determining the fill level. In this way it ispossible to achieve an accuracy of measurement that is much better thanthat achieved in the methods of the prior art.

A further development of the method comprises the following steps:

-   -   acquiring three-dimensional data of the container with a mobile        end device, having at least one optical camera, a depth sensor        and a motion detector,    -   establishing a three-dimensional model of the container, and    -   calculating the linearization curve from the three-dimensional        model for determining a fill level from a measured filling        height.

According to the further developed method, three-dimensional data of thecontainer are acquired with the aid of the mobile end device, whichcomprises at least one optical camera for capturing and visualizing animage of the container, a depth sensor for detecting the distance ofindividual points of the container surface from the mobile end device aswell as a motion detector for detecting at least one relative movementof the mobile end device. The use of a depth sensor and a motiondetector makes it possible to automate the acquisition of the referencevalue and the symmetry of the container; and it makes it easy to takeinto account, in particular, complex symmetries. It is even possible todetect containers without a simple symmetry. From the three-dimensionaldata of the container, which can be determined, in particular, from thedata acquired with the aid of the depth sensor and the motion detector,it is possible to create, preferably with the mobile end device, athree-dimensional model of the container with a high degree of accuracy.Preferably the three-dimensional model of the container is vector-based.

As soon as the three-dimensional model of the container is completelyfinished and available for the relevant parts of the container, saidthree-dimensional model of the container can be used to calculate,preferably with the mobile end device, the linearization curve fordetermining the fill level in the container, based on a measured fillingheight. Since the three-dimensional model of the container that isestablished in this way and the linearization curve that is calculatedfrom said three-dimensional model take into account the actual localconditions, it is possible to consider, in particular, theirregularities of the container, the built-in components and/or otherspecial features when determining the fill level. In this way it ispossible to achieve an accuracy of measurement that is much better thanthat achieved in the methods of the prior art.

In a simple variant of the method according to the invention, thethree-dimensional data of at least one outer shell of the container areacquired. Owing to the acquisition of the three-dimensional data of theouter shell of the container it is already possible to obtain,preferably with information about, for example, the wall thickness ofthe container, very good linearization curves for determining the filllevel inside the container from the filling height.

In a preferred variant of the method according to the invention, thethree-dimensional data of an inner shell of the container are acquiredin addition to or as an alternative to the three-dimensional data of theouter shell of the container. With the aid of the three-dimensional dataof the inner shell of the container, i.e., in particular, the innerdimensions and the built-in components, an exact linearization curve fordetermining the fill level inside the container can be calculated fromthe filling height. In this way it is possible to take into account, inparticular, the influences of the built-in components on the fill level,so that very exact measurement values can be obtained.

The acquisition of the three-dimensional data of the container can becarried out, in particular, in accordance with one method or acombination of the methods: time of flight, structured light orstereoscopy. The aforementioned methods constitute different methods foracquiring depth information by means of the measurement of the time fromthe emission of a light pulse until the reception of the light pulsereflected from the object to be measured (time of flight), theprojection of a structured light carpet, for example, a grid or pointson the object to be measured and the detection of the projection(structured light) or the utilization of stereoscopic effects for dataacquisition of the depth and size of the object to be measured, in thiscase, the container.

The three-dimensional acquisition of the container can be facilitated,for example, by means of a database with three-dimensional data ofpossible built-in components. For example, three-dimensional data of aplurality of built-in components that are typically used in, forexample, tanks or silos, can be stored in such a database and can beretrieved in order to help establish the three-dimensional model. Inthis way, in particular, built-in components with complex geometricshapes can be easily detected and taken into account.

Furthermore, in addition to the linearization curve, a suitable filllevel measuring method and/or an optimized position for a fill levelsensor can be determined and outputted. By knowing the concrete geometryof a container and the local built-in components, an optimized choice ofa fill level measuring method can take place here by, for example, ananalysis of the emission cones, needed by certain measurement methods,with respect to a free space, in which this measurement can occur.

Inventive is also the use of a mobile end device having at least oneoptical camera, a depth sensor and a motion detector for acquiringthree-dimensional data of a container, for establishing athree-dimensional model of the container as well as for calculating alinearization curve for determining a fill level from a filling height.

DETAILED DESCRIPTION OF THE FIGURES

FIG. 1 shows, as an example, a container 10, for which a linearizationcurve L for determining the fill level F from the filling height h is tobe calculated. In the present exemplary embodiment the container 10 isdesigned as a silo with a circularly cylindrical main body and atruncated conical bottom portion that is disposed on the underside ofthis main body and is designed for attaching an outlet. Furthermore, thesilo 10 has four supporting feet and a corresponding cover lid.

Furthermore, FIG. 1 shows a mobile end device 12, which is configuredfor acquiring three-dimensional data of objects. In the presentexemplary embodiment the mobile end device 12 is designed as a tabletcomputer, but it could also have the form of a mobile telephone, a videocamera or a photo camera or the like.

The mobile end device 12 from FIG. 1 is shown on an enlarged scale inFIG. 2. It can be seen in FIG. 2 that the mobile end device 12 has anoptical camera 14, a depth sensor 16 and a motion detector 18. Theoptical camera 14 is used in essence to capture an image of an object tobe measured and for outputting this image on a screen of the mobile enddevice, so that in this way a user can see a region of the capturedimage directly on the mobile end device.

The depth sensor 16 can acquire information about the depth and size ofthe object to be detected by using various methods. In the presentexemplary embodiment the depth sensor 16 is designed with an infraredprojector for projecting a structured infrared light carpet on theobject to be detected and with a corresponding infrared sensor fordetecting the light carpet on the object. An analysis of the reflectedlight carpet and its distortions produced on the object to be measuredcan be used to draw conclusions about the geometry of the object to bemeasured and about its size.

Both the depth data and the size data that pertain to the object to bemeasured and that are acquired from various positions can be broughttogether by means of the motion detector 18, which detects the relativemovements of the mobile end device 12; and, as a result, a completethree-dimensional model of the object to be measured can be calculated.

At this point it should be mentioned that the depth sensor 16 can alsooperate by means of other suitable methods, for example, by usingstereoscopic effects and/or by means of a plurality of distancemeasurements by determining the time between the emission of a lightpulse and the arrival of its reflection or a combination of thesemethods also with the structured light method described above.

FIG. 3a ) shows, as an example, the three-dimensional model 8 of thecontainer 10 from FIG. 1. In the present exemplary embodiment both theouter shell 101 and the inner shell 102 of the container 10 weredetected. Furthermore, in the course of detecting the inner shell 102,the built-in components 103, which may be found in the container 10,were also detected, so that in this case a very detailedthree-dimensional model 8 was created.

At this point it should be noted that it is also possible to acquire,depending on the requirements of the individual case, just thethree-dimensional data of the outer shell 101 or the inner shell 102and/or the built-in components 103.

The linearization curve L (shown in FIG. 3B)) for determining a filllevel F from the filling height h was calculated from thethree-dimensional model 8 of the container 10 (shown in FIG. 3A)),taking into account the acquired three-dimensional data. It can be seenin FIG. 3B) that, in particular, the built-in component 103, which canbe seen in FIG. 3A), was considered in this linearization curve L.

LIST OF REFERENCE NUMBERS

-   8 Three-dimensional model-   10 container-   12 mobile end device-   14 camera-   16 depth sensor-   18 motion detector-   L linearization curve-   h filling height-   F fill level-   d material thickness-   101 outer shell-   102 inner shell-   103 built-in components-   8 three-dimensional model

The references recited herein are incorporated herein in their entirety,particularly as they relate to teaching the level of ordinary skill inthis art and for any disclosure necessary for the commoner understandingof the subject matter of the claimed invention. It will be clear to aperson of ordinary skill in the art that the above embodiments may bealtered or that insubstantial changes may be made without departing fromthe scope of the invention. Accordingly, the scope of the invention isdetermined by the scope of the following claims and their equitableequivalents.

I claim:
 1. A method for determining a fill level in a container from ameasured filling height using a mobile end device, the method comprisingthe following steps: acquiring, by at least one optical camera,two-dimensional data of the container and a reference value of thecontainer having an image symmetry of the container with the mobile enddevice, establishing a three-dimensional vector model of the containerusing the two-dimensional data, the reference value and informationabout the symmetry of the container, and calculating a linearizationcurve from the three-dimensional vector model for determining the filllevel from the measured filling height.
 2. The method of claim 1,wherein the three-dimensional data of at least one outer shell of thecontainer are acquired.
 3. The method of claim 2, further comprisingwherein a material thickness of the container is entered.
 4. The methodof claim 1, wherein the three-dimensional data of an inner shell of thecontainer are acquired.
 5. The method of claim 1, wherein theacquisition of the three-dimensional data of the container occurs inaccordance with one or a combination of the methods: time of flight,structured light or stereoscopy.
 6. The method of claim 1, wherein thethree-dimensional acquisition of the container is supported by means ofa database with three-dimensional data of possible built-in components.7. The method of claim 1 further comprising, wherein, in addition to thelinearization curve, a suitable fill level measuring method and/or anoptimized position for a fill level sensor is/are determined andoutputted.
 8. A system for determining a fill level in a container froma filling height, the system comprising: a mobile device having at leastone optical camera; the mobile end device configure to acquiretwo-dimensional data of the container and a reference value of thecontainer having an image symmetry of the container with the mobile enddevice using at least one optical camera, establish a three-dimensionalvector model of the container using the two-dimensional data, thereference value and information about the symmetry of the container, andcalculating a linearization curve from the three-dimensional vectormodel for determining the fill level from a measured filling height.